Re: tipc_init(), WARNING: at arch/x86/mm/highmem_32.c:52, [2.6.24-rc4-git5: Reported regressions from 2.6.23]

Linus Torvalds
2007-12-08T17:49:18Z

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On Sat, 8 Dec 2007, Matt Mackall wrote:
>
> Avoid calling page allocator with __GFP_ZERO, as we might be in atomic
> context and this will make thing unhappy on highmem systems. Instead,
> manually zero allocations from the page allocator.

I think this is fine, but didn't we fix the warning already? Calling page
allocators with __GFP_ZERO should be fine, as long as __GFP_HIGHMEM isn't
set, and slab/slub/slob/kmalloc cannot use GFP_HIGHMEM *anyway*.

But I'll apply it anyway, because it looks "obviously correct" from the
standpoint that the _other_ slob user already clears the end result
explicitly later on, and we simply should never pass down __GFP_ZERO to
the actual page allocator.

On that note, shouldn't we also do this for slub.c? Christoph?

Linus

---
mm/slub.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index b9f37cb..9c1d9f3 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1468,6 +1468,9 @@ static void *__slab_alloc(struct kmem_cache *s,
void **object;
struct page *new;

+ /* We handle __GFP_ZERO in the caller */
+ gfpflags &= ~__GFP_ZERO;
+
if (!c->page)
goto new_slab;